Integrated adder drive assembly including damper, hydraulic power supply, and paper tape feed

ABSTRACT

A digital hydraulic system converts binary digital input information into displacement of a digital drive. An air reader is used to operate binary latch valves through an air hydraulic interface. A flow sensing system and a hydraulic logic unit cooperate to provide high speed exchange between the piston adders of the digital drive prior to displacement of the load. A hydraulic cylinder sweeps the load about a vertical axis. A selfcooling, air-driven hydraulic pump with an accumulator, provides relatively constant pressure. A damper secured to the piston adders has an additional drive for providing precise location at the end of damping. An incremental paper tape feed with a four motion rack with toggle action indexes the air reader.

United States Patent Panissidi INTEGRATED ADDER DRIVE ASSEMBLY INCLUDING DAMPER, HYDRAULIC POWER SUPPLY, AND PAPER TAPE FEED l-lugo A. Panissidi, Peekskill, N.Y.

International Business Machines Corporation, Armonk, N.Y.

Filed: May 14, 1969 Appl. No.: 824,424

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 1l/1969 Devol ..92/9X 1/1958 Randall ..92/10X Primary ExaminerEdgar W. Geoghegan Assistant Examiner-A. M. Ostrager Attorneyl-lanifin and Jancin and Graham S. Jones, II

[57] ABSTRACT A digital hydraulic system converts binary digital input information into displacement of a digital drive. An air reader is used to operate binary latch valves through an air hydraulic interface. A flow sensing system and a hydraulic logic unit cooperate to provide high speed exchange between the piston adders of the digital drive prior to displacement of the load. A hydraulic cylinder sweeps the load about a vertical axis. A selfcooling, air-driven hydraulic pump with an accumulator, provides relatively constant pressure. A damper secured to the piston adders has an additional drive for providing precise location at the end of damping. An incremental paper tape feed with a four motion rack with toggle action indexes the air reader.

6 Claims,-l7 Drawing Figures PATENTEDAPRWWZ 3.726.190

SHEET UlUF 14 e 11 14 SWITCHING 15 1o VELOC'TY 141,342 HYDRAULIC MR 12 Am 7 CONTROL if}?! HYDRAULIC READER VALVE VALVES INTERFACE RESET w --4%z%zw 52 wk 16 EXCHANGE,"

& MOVE HYDRAULIC P'STON J DAMPER FLOW POWER ADDERS SENSING SUPPLY 156 1g SYSTEM 75 76/ mg; -amw 11s CONTROL "3;

94 HYDRAULIC LOGIC s IAR T I o -o 94 2o DECODER 50 WITH ALIGNERS TREE k was 25 32/ CLAMP RACK 2oo- -19a 190 33\ F 206 g \zosi SWEEP CYLINDER 33 SWEEP "Q g SENSE r T INVENTOR 204 uuco A. PANISSIDI BY M ATTORNEY PATENTED APR 1 o m sum OEUF 14 om 2 6a hi3 HNdE INdE

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FIG.

FIG.

ISOLATION VALVE 0- PURCE CONTROL VALVE O- LOAD VELOCITY CONTROL VALVE O- READER RACK PISTON O- READER TOCGLE VALVE--O ALICNER PISTON -O ALIGNER DELAY PISTON-O- ALICNER VALVE- ALICNER LATCH VALVEO- DAMPER PlSTON-- O- DAMPER DELAY PISTON- O- 3 DAMPER VALVE 0 I U E EXCHANGE VALVE-- O- MOVE VALVE 0- E MOVE SENSE VALVE-O N02 LATCH VALVE 0 N02 PILOT VALVEO MOVE DELAY PISTON 0 now VALVE --o now VALVE msmu-o 4OMS ZONS

START VALVE *O PROBE DELAY PISTON ---O PROBE VALVE PROBE PHASE PISTONO 0 2O 4O 6O 80 I00 I20 I40 160 I80 200 TIME IN MILLI SECONDS PATENTEO APR I 0 5 SHEET 130E 14 FIG. 3B

TIME IN MILLISECONDS ISOLATION VALVE PURCE CONTROL VALVE LOAD VELOCITY CONTROL VALVE READER RACK PISTON READER TOCCLE VALVE ALICNER PISTON ALICNER VALVE ALICNER DELAY PISTON ALICNER LATCH VALVE DAIIPER PISTON DAMPER DELAY PISTON DAMPER VALVE EXCHANCE VALVE NOVE VALVE MOVE SENSE VALVE EXCHANGE SENSE VALVE BYPASS POPPET I" CYLINDER NO. I LATCH VALVE 2" CYLINDER NO.2 LATCH VALVE NO.2 PILOT VALVE NOVE DELAY PISTON FLOVI VALVE FLOIV VALVE PISTON START VALVE PROBE VALVE PROBE DELAY PISTON PROBE PHASE PISTON INTEGRATED ADDER DRIVE ASSEMBLY INCLUDING DAMPER, HYDRAULIC POWER SUPPLY, AND PAPER TAPE FEED CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to U.S. Pat. No. 3,575,301 issued based on Ser. No. 694,941. entitled Manipulator, U.S. Pat. No. 3,550,630, issued based on application Ser. No. 695,139 by H.A. Panissidi entitled Serial-to-parallel Hydraulic Device, and U.S. Pat. No. 3,641,877 issued based on Ser. No. 824,425 entitled Flow Sensing System and Valve by R. C. Hebert, filed herewith.

BACKGROUND OF THE INVENTION zero or neutral position. However, previously known damping mechanisms in the art have not included any means for precisely locating the moveable mechanism relative to a fixed member. Accordingly, in connection with accurate digital drives, it is highly desirable to provide some means for providing damping and at the same time including control mechanism and means for precisely locating the load at the end of the displacement cycle.

Prior air driven engines have toggled relatively slowly thereby causing a fairly high degree of regulation or fluctuation in output pressure from the oil pump. Faster systems have often employed electrical motors which have created a significant heat dissipation problem. External cooling arrangements have been supplied for such systems including radiators, circulation of oil to the radiators on the exterior of the system. Such radiators require space and are costly.

Many previous paper tape feeding mechanisms have required a number of parts. Usually they have involved many costly gears and linkages.

SUMMARY OF THE INVENTION In accordance with this invention means are provided for damping motion and subsequently accurately locating the damped member relative to a predetermined location. In connection with digital drives, means are provided of accurately locating the first member of the digital drive relative to a zero position after each operation of the digital drive to displace the load in a predetermined direction has been accomplished.- In another aspect, means are provided for initially cocking the damping mechanism into a position in the opposite direction from the final direction of displacement. Subsequently, upon deceleration by the damper with minimum overshoot, the load is caused to locate by positive locating means in the damper.

In another aspect of this invention, means are provided for pumping hydraulic fluids by means of an air engine, having a high speed of toggling, by employing an impact and a toggle action which causes the air engine to reverse direction rapidly upon approach of completion of travel of the hydraulic piston towards one extreme position thereof.

In another aspect of this invention, the integral hydraulic power supply includes a built in accumulator and self cooling by means by the effluent, escaping and expanding air from the air engine and the entire hydraulic pressure supply system is housed within the hydraulic unit.

In accordance with another aspect of this invention a paper tape feed is provided which includes a reciprocating rack which is driven through four motions. In another aspect a toggle action form of rack engagement with a drive for a paper tape is actuated by means of a pair of hydraulic valves.

An object of this invention is to provide accurate location of a digital drive subsequent to the major displacement motion of that drive and damping thereof.

A further object of this invention is to provide means for efficient damping of a drive subsequent to displacement of the load.

Another object of this invention is to provide means for cocking a damping mechanism prior to damping. A related object is to provide damping with minimum overshoot.

An object to this invention is to provide means for reversing the direction of operation of an air engine prior to the time that the pump being driven thereby reaches its extreme position.

Another object of this invention is to provide an air driven engine and pump wherein cooling of the output fluid is provided efficiently.

- Still another object of this invention is to provide a hydraulic pressure supply system wherein the output pressure is relatively constant during the interval between strokes of the hydraulic pump.

Another object of this invention is to provide a feed advancing mechanism having a relatively small number of parts.

Another object of this invention is to provide a feed advancing mechanism which is readily controllable by means of a fluid control system.

Still another object of this invention is to provide an incremental drive for feeding.

A further object of this invention is to provide a four motion rack engaging mechanism for a feed device.

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic block diagram of the overall system employed in accordance with this invention.

FIG. 2 shows the relationship between the various sections of the large diagram of FIGS. 2A-2K.

FIGS. 2A-2K show the overall connections between the various subsystems of the integrated adder drive assembly employed in accordance with this invention, and in FIGS. 2K and 2L additional details of the system are shown.

FIG. 3 shows the relationship between FIGS. 3A and FIGS. 3A and 3B show the displacement characteristics of valves and mechanism in the hydraulic system shown in FIGS. 1 and 2A-2K in accordance with this invention as a function of time.

FIG. 4 shows the sweep and arm clamping mechanisms for the base of a manipulators arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Control System Referring to FIG. 1, the present system includes an air reader 10 for reading a perforated tape 11 which provides output pulses to a hydraulic control system by means of an air line 12 and an air hydraulic interface 13 which converts pneumatic pulses to hydraulic values. The air hydraulic interface transfers pulse inputs to hydraulic binary latch valves 14 which remember or retain a or'a 1 condition, depending upon the sense or polarity of the input transmitted from reader through the interface 13.

The outputs of the latch valves are in general connected via lines 141, 142 to extend or retract a corresponding one of a several piston adders 15 which comprise a series of interconnected pistons and cylinders employed to provide binary displacement of a load bearing shaft 156 by unit distances, in binary progression from from l/32 inch to almost 32 inches in binary steps up to 16 inches.

For the l, 2, 4, 8 and 16 inch long piston adders, a set of variable orifices in a velocity control valve 17 are 7 provided between lines 141, 142 and .342 for the purpose of controlling the rate of displacement of the pistons with larger displacements.

In order that the piston adders 15 and the output shaft 156 connected to one end thereof may be accurately located rapidly, a damper 18 is provided which permits the piston adders 15 to be cocked during an exchange interval.

The exchange interval is a time during which the output shaft 156 is firmly retained in position by braking or arresting means shown in part herein and shown in full in above U.S. Pat. No. 3,575,301 and the piston adders 15 are reset and extended to the extent that certain pistons are retracted and certain other pistons are extended. During the exchange period the velocity control valve 17 will he held wide open to permit exchange at maximum permissable velocity, since the piston adders 15 will not be under load. See above U.S. Pat. No. 3,641,877.

Referring again to the damper 18, when the load has been fully positioned where desired, the damper 18 provides hydraulic damping with minimum overshoot and is actuated via line 75 by hydraulic logic unit 20 to provide mechanical positioning ultimately to a precise home position. Cocking minimizes overshoot and optimizes use of time for the steps of exchanging piston locations and driving the load.

In order to provide regulated hydraulic pressure to the system a hydraulic power supply 22 is provided. It supplies pressure for latching and to the central lands 16 of spool valves in the hydraulic logic unit via line 116 and the flow sensing system 23, via line 47, which controls two bleed lines 24 and 25 to the hydraulic logic unit 20 as a function of the velocity of flow through line 47, the flow sensing system 23 and line 52 to the latch valves 14 which connect to the piston adders 15. When the flow or displacement of piston adders declines below a minimum value the bleed lines 24 and 25 are blocked by flow sensing system 23. A bypass control line 38 from the hydraulic logic unit 20 controls a port 40, 41 inside the flow sensing system 23 to control one of the flow sensing units therein.

The hydraulic logic unit 20 can be started and stopped. Since the logic unit 20 controlsthe toggle line 76 which powers the feed advance of the tape reader 10, when switch 54 is operated, air is blocked from operating the logic unit 20 and at the end of a displacement cycle operation of the system stops.

As the drive is adapted to displace a plurality of members, a decoder 30 is connected to the logic unit 20 via line 94, and to certain ones of the latch valves 14, to operate aligners 31 to hold the various members to be displaced by the output shaft, through a linkage, not shown, which is similar to that shown in U.S. Pat. No. 3,575,301. Clamp rack 32 is engaged when it is desired to drive the Z-arm of the output, for example, a manipulator, as shown in FIG. 4.

A set of sweep sense units 33 and a sweep cylinder 34 are employed to sweep a load on support about an axis upon an input via line 198 or 200 from one of the latch valves 14. The sweep sense unit 33 is connected to bleed line 25.

Referring to FIGS. 2A-2J, the overall system is shown in greater detail than in FIG. 1 and the connections between the various systems are shown.

Exchange and Variable Velocity Control The exchange and move flow sensing system 23 includes a cylindrical exchange sense piston 35, a cylindrical move sense piston 36 and a bypass poppet 37. The bypass poppet 37 is controlled by pressure in a line 38 connected to the lower output of flow spool valve 39 in FIG. 2B. When the bypass poppet 37 is to the left, its valve 40 will seat on surface 41 to close off the inlet 42 to the exchange sense piston 35. It should be noted that the exchange sense piston 35 and the move sense piston 36 are each spring biased by springs 43, coaxial therewith in the larger coaxial bore 44 in the pistons 35 and 36. The pistons 35 and 36 are grooved at 45 to connect the bleed lines 24 and 25 to the return 46 to the low pressure side of the hydraulic pressure supply 22. Pressure from the hydraulic pressure supply 22 is supplied by line 47 to the inlet 48 on the upstream end of the valve 40 of the'bypass poppet 37 which may or may not be open, as described above, and to the inlet 49 to the move sense piston 36. Each of the exchange sense piston 35 and the move sense piston 36 is provided with a smaller axial bore 50 to the upstream end thereof confronting the corresponding inlet 42 or 49'thereof. The orifices 50 are selected so that when the pressure differential across the orifice 50 is above a predetermined level, then the pistons will be driven upwardly against the pressure of the springs 43 to align the grooves 45 with the bleed lines 24 and 25, thereby connecting the bleed lines to return 46. The bypass poppet 37 provides a means for selectively actuating the exchange sense piston 35. In this way, the flow sensing system may be operated in two modes depending on whether the piston adders are being driven in the move or exchange mode of operation. A further feature of this system is that since each of the orifices 50 is substantially of the same order of magnitude in diameter and length, the resistance to fluid flow provided by each thereof is substantially of the same order of magnitude. When both are connected in parallel, the resistance to flow is nearly halved, or conversely, flow doubles, approximately. As will be noted, the outlets 51 of the two sense pistons are connected to line 52. Since the two sense pistons are in parallel, and therefore the orifices 50 are in parallel, if the bypass valve 40 is open, the quantity of flow through each of the two orifices 50 will be substantially equal and accordingly the rate of flow into the line 52, if sufficiently large and unrestricted will in general be approximately doubled. Accordingly, when the exchange sense piston 35 is permitted to operate by the bypass poppet 37, the quantity of fluid flowing from lines 51 through line 52 to the piston adder drive will be greater and the velocity of displacement in the exchange period will accordingly be far greater (.See US. Pat. No. 3,641,877 for a more complete description under this section). Hydraulic Logic Unit The hydraulic logic unit comprises a plurality of spool valves, delay pistons in cylinders which comprise compliance or capacitive units which require a time delay for displacement from one end to the other end of the cylinder in which they are housed; orifices, check units described below in connection with FIG. 2L, interconnections and outlets which control other elements of the overall system. Certain of the spool valves are spring biased into one position as indicated by helical springs in longitudinal cross section. Certain other of the spool valves are latch valves which are held in position by hydraulic latching means.'Such a latching means comprises a passageway 600 tangential to one end of a landof a spool located so thatit supplies fluid under pressure to the side of the land regardless of spool position, and contacts a small area on one side. The land thereby creates a laminar pressure gradient along that side which is coupled to the return lines through leakage. There is a ratio of pressures across the land of several times the pressure on the inlet side to the pressure on the low pressure side which pushes the land to one side and inhibits longitudinal sliding because of friction forces. Pressure can be relieved during movement of the spoolsto relieve friction forces.

When the start diaphragm 56 is operated by the pressure at inlet 53 (assuming pneumatic toggle 54 in on) from the reader start apertures 28 in the tape via line 29, or otherwise provides input from a two way solenoid or valve 27, etc., then the start spool valve 55 is driven upwardly thereby connecting its lines 57 to the right and to the left to higher pressure from the central annular groove 16 as the central land or ring passes thereabove. Accordingly, pressure will be applied at the junction 58 between the orifice checks (described below in connection with FIG. 2L, 59 and 60 which connect to the probe spool valve 61, the probe delay piston 62, and the probe phase piston 63. On the left side, the line 57 is connected to the point 64 which supplies the lower end of flow spool valve 39; and by orifice check 65 point 64 is connected to line 66 and phase piston 67. It will be noted that line 66 is connected to bleed line 25 and both are connected to the upper end of the flow spool 39, valve which is spring biased downwardly. Accordingly, when the flow phase piston 67 has moved fully to the top of its cylinder at the end of 60 milliseconds, then as soon as the exchange sense valve causes the bleed line 25 to be disconnected from the return 46, the pressure on the line 25, and therefore on the upper end of the flow spool valve will be increased and the flow spoolvalve will be driven back to its position as shown in FIG. 28 by the force of the spring 87. Initially, then, as soon as the start valve is operated, the flow valve will be operated also and pressure will be placed upon line 38 from the central high pressure source and line 38 will connect pressure to the bypass poppet, which will remain open until the flow valve is driven back to its home position. Since line 38 is connected to the lower end of delay piston 68 and to the lower end of move spool valve 69 which is biased upwardly, the move valve will be driven rather rapidly upwardly shortly after the flow valve is driven upwardly, by the spring 53. It should be noted that later, when flow is reversed, the delay piston 68 cooperates with the orifice check 70 to provide a long time delay before it is possible for the move valve 69 to be reset down against the force of its spring 53. When the move valve is driven upwardly, the line 71 from the upper end thereof has the pressure thereon released, thereby releasing pressure on the upper end of the exchange spool valve 72 which will have pressure on the lower end thereof from the line 38 which, after the delay valves have permitted the pressure to build, will then shift upwardly. The damp spool valve 73 has a spring bias at the lower end thereof, and will shift shortly after the exchange valves shifts, thus releasing the pressure from the upper end thereof. Line 75 is connected to the damper 18 including its pistons as shown in FIG. 1 and FIG. 2] secured to one end of the piston adders 15. At this point in each displacement I cycle of the drive, pressure is released from the damper positioning pistons 80. Accordingly, the damper is released so that it can be cocked during the exchange mode of operation. After an interval of about 20 milliseconds selected to allow pilot valves to be positioned, according to the data in the tape, the probe delay piston 62 will have reached the opposite end of its cylinder. Accordingly, the pressure at the lower end of the probe spool valve 61 will have reached a high enough level to overcome the spring biasing force at its upper end and to drive the valve upwardly thereby providing pressure on probe line 81 from the central annular pressure source 82 as the central land passes thereacross and the lower land passes across the return 83. The probe line 81 is connected to each of the inlets 84 of the pilot valves 85 to provide pressure to their central annular cavities. The probe pressure is employed to adjust the hydraulic binary latch valves 14 in accordance with the binary values provided by the air reader 10. Thus, the binary drive will be reset in accordance with the most recent input data provided thereto in the tape under the air reader). It will be understood that another varity of input source could be connected through a suitable interface. About 40 milliseconds after start, the probe phase piston 63 will rise to the top of its somewhat longer cylinder and at that time will cause a pressure build up at its lower end, which is connected to the upper end of the probe spool valve 61 which is spring biased downwardly. Since the pressures of the opposite ends of the probe spool valve 61 will be equal and opposite, accordingly, the probe spool valve will be driven downwardly by its spring 86. At this time pressure will be removed from the probe line 81. This will now mean the end of the exchange motion of the piston adders which will be under control of the hydraulic latch valves 14 which will remain as positioned during the probe portion of the control cycle of the hydraulic logic circuit 20. So long as the exchange continues, the exchange sense piston 35 will remain in its upper position against its spring as will the move sense piston. At a predetermined point, when the exchange velocity ends and the flow of hydraulic fluid due to elimination of pressure differential and the end of flow through the sense pistons 35 and 36, they will both move down to their spring biased lower positions. Accordingly, bleed line 24 will be closed momentarily 39 will, as described above, have been driven downwardly thereby connecting line 38 to the return 95. Pressure on line 76 from aligner latch valve 74 in FIG. 2A to the reader 10, FIG. 2D, will operate the reader feed mechanism. In addition in the purge control in FIG. 2B, pressure in line 76, will operate a pair of pistons 96 from line 97 attached to the line 76 to drive the spool valves 98 and 99 to the left so that the pressure on line 100 will be connected down into the lines 101 which are connected to the purge inlets to the diaphragms 102 in the air hydraulic interface 13. Air under 10 psig pressure will be driven through the purge inlets 101 across the surface of the diaphragms of the interfaces 102 and out through the reader lines 12 to purge or to drive oil out of the system and to clear and chad and other material from the lines 12, and 112.

v The remainder of the purge cycle is described below,

and bleed line 25 will be closed for the remainder of each cycle of operation of the hydraulic logic unit 20. Line 25 will thereby cause build up of pressure on the upper end of the flow valve 39 as mentioned above and the spring 87 at the top thereof will act to drive the flow valve 39 down. Pressure will build on the line 24 and line 89 from lines 16 and 688 through the flow valve 39. However, the delay piston 68 and the orifice in orifice check 70 will defer the build up of the pressure in the lines 24 and the build up of the inlet 89 to move valve 69, and actually the move valve 69 will not be operated at this time, because, a short time later, bleed line 24 will be reconnected by move sense piston 36 to the return 46 and will bleed pressure from inlet 89. Line 688 will apply pressure immediately to the central cylindrical cavity 188 of the exchange spool valve 72 held up by pressure in line 38 and thereby providing pressure on line 90 to the lower end of the aligner latch valve 74. The aligner latch valve 74 will be driven upwardly since the upper end thereof will have low pressure, as on line 75. The pressure had been released as described above. Accordingly, the aligner latch valve will release pressure on line 91 to permit the aligner spool valve 92 to be driven upwardly by a spring 93. This will apply pressure to line 189 resetting start spool valve 55 applying pressure from line 116 to reset line 88 to reset all of the pilot valves 85 and will release pressure from line 94 which is connected to the aligners 31 so that one of the members connected to the output of the load shaft, can be driven at this point. Further, line 94 is also connected to the velocity control valve 17 in order to reduce the orifice into the piston adders during the period of driving of the load. As the load is now free to move, the piston adders can move and accordingly flow will resume in line 52 (as indicated above in connection with line 24) and for that reason the pressure drop across the move sense piston will resume and the move sense piston will be driven upwardly again thereby bleeding pressure from the bleed line 24. However, the bypass poppet 37 will have pressure released therefrom on line 38 since the flow valve after discussion of concurrent valve operations.

The pressure will remain on line-76 until such time as the motion of the piston adders ends and the move valve 69 is driven downwardly by final closure of the bleed line 24 by closure of the move sense piston 36, so that at that time, line 71 will drive the exchange valve 72 down removing pressure from line 90 and at the same time applying pressure to line 103 through the orifice of orifice check 104 and delay piston 105 after a time delay of 90 milliseconds, drive the damp valve 73 down against its spring and to apply pressure on line 75 therefrom to drive the aligner latch valve 74 down and remove pressure from line 76 and apply pressure to line 91 and through the orifice in the orifice check 106 and delay piston 107 cause a time delay to run to drive the aligner valve 92 down against its spring 93. The aligner delay piston 107 will require another 120 milliseconds to drive downwardly. Accordingly, final alignment will not occur for some time.

However, referring again to the purge unit, in FIG. 28, when line 71 is pressurized, the piston 99 will be driven to the right and atmospheric pressure from line 199, to atmosphere, will be permitted to resume inside the purge and reader lines 101 and 12 so that the diaphragms 102 may be returned to atmospheric pressure. Then when pressure is removed from line 76 as a result of return of the aligner latch value to its lower position, the spring 108 of the spool valve 98 will act to drive that spool valve to the right and to shut off connections 101 to the diaphragms. It should be noted that the 10 psig air supply 109 is connected to line .110 which applies positive pressure to the air pressure head 1 l 1 for passage through the tape 1 1 into the inlets 12 to the diaphragms 102.

During the time that the purge spool valve 98 is to the left, the blocking of pressure by valve 98 from line 110 to the air reader 111 will prevent blowing air down into the diaphragms during the purge cycle when air is to be blown in the reverse direction.

Air Reader The perforated tape reader shown in FIG. 2D will operate in ordinary machine shop air typical of industrial locations, which is contaminated with dirt, oil and water. Therefore, cyclic purging of lines 12 is necessary because the reader sense hoses are extremely thin,

usually 0.030 inches I.D. making them vulnerable to clogging.

In order to avoid costly memory devices and serial to parallel converters for some applications, the reader is designed to advance the tape up to two characters per step, allowing the system to accept two characters of data simultaneously. The hydraulically driven reader, as shown schematically, consists of an air reader head with 16 ports to accept two perforated characters of an eight-channel Mylar tape. The 16 ports of the air reader head are connected by sense hoses to the 16 diaphragm driven hydraulic pilot valves. The air reader head, supporting the tape, is pressurized with 10 psig air by a spring loaded air manifold. A hole in the tape will allow its corresponding diaphragm actuated pilot valve to be pressurized with 10 psig from the air manifold.

The air reader 10 includes an air pressure head 111 which is spring biased downwardly by a spring 117. The tape which is used includes eight longitudinal columns and is read in groups of two rows of characters such, as shown in FIG. 2D, simultaneously. Accordingly, the feed must advance two rows of holes for each reading cycle. The top hole in the first row is the start control. The next two holes are M2 and M1 controls for FIG. 2E

and the next holes ones are the fractions from one-half inch down to one thirty-second inch. In the second column in the second hole, the sweep mode of operation of the manipulator which would be attached to the device is entered and in the third hole, the bit for the grip mode of operation of a manipulator gripper would be entered. In the last five holes in the second column, the bits for the 16, 8, 4, 2, and l-inch piston adders would be entered. The head 111 is designed so as to provide air pressure above all 16 holes and underneath the holes would be aligned the various inlets 12 to the diaphragms 102 shown in FIGS. 2E-2I-I. The feeding mechanism is comprised of a sprocket wheel 118 which operates in cooperation with perforations 119 in the tape 11. The sprocket wheel 118 is secured to shaft 120 and the shaft 120 is journalled for rotation in response to torque applied by gear 121 which is retained in position by detent pawl 122 which is spring biased downwardly by spring 123. The pawl 122 carries a pin 124 at one end thereof which fits into the teeth of gear 121. The gear 121 is adapted to mesh with a rack 125 which can be raised into gear by a toggle lever 126 which is pivotally secured by pin 127 in which toggle lever carries rack 125 on pin 128. The rack 125 is reciprocably longitudinally slideable on drive wire 129 secured at its distal end to a piston 130 slideably carried in cylinder 13] for longitudinal reciprocation therein. The cylinder 131 contains a spring 132 at the distal end of the piston 130 for biasing the piston 130 leftwardly. At the opposite end of the cylinder is a release aperture 333 to permit motion to the right. The opposite end of the toggle lever 126 is secured to a drive wire 133 by means of pin 134 to bifurcated end 135 of drive wire 133. Drive wire 133 is secured at its distal end to a spool valve 136 carried in cylinder 137. The spool valve 136 is spring biased leftwardly by spring 138. At the leftward end of piston 130 is an inlet 139 connected from the central portion of cylinder 137 adapted for communication with the two inlets 81 and 281 into the lower cylinder 137 from the central portion thereof. At the leftward extreme end of cylinder 137 is located an inlet from line 76 from the aligner latch valve lower outlet, which is provided for operating the reader. If pressure were applied to line 76, it would function to pull the toggle lever 126 counterclockwise about pin 127 by means of flexing of drive wire 133. Lever 126 and pin 128 will drive the rack 125 up into engagement with the gear 121 preparatory to actual driving motion. When this occurs, i.e., valve 77' is to the right, the connection of line 139 to the cylinder 137 will be made to the line 116. This will drive the piston 130 to the right against the reaction of its spring 132 pulling wire 129 and the rack 125 to the right and turning the gear 121 counterclockwise about shaft 120 thereby advancing the tape 11 two character positions to the left as the sprocket 118 is turned on the shaft 120 counterclockwise. It should be noted that while the probe pressure is employed for the purpose of driving the air reader, that such probing does not occur until after the pressure on the purge line 76 has been generated by means of driving the aligner latch valve 74 to its upper position after the exchange is terminated. The adjustment of the pilot valves during the probe cycle will have been completed well prior to that time; and with the application of pressure on line 76, and the displacement of the purge spool valve 98 to the left, the pressure applied on line 110 to the air pressure head 111 will have been blocked by the leftward land of the spool valve 98.

During the period the rack rotates the drive gear, there is a substantial separating force between the rack and gear due to the pressure angle of the gear teeth (20) which is supported by the toggle shaft.

With pressure removed from the left end of the toggle valve, its spring will drive it to the left rotating the toggle lever 126 to its initial position. The toggle valve will expose port 139 to its port 281, thereby removing pressure from the left-hand side of the drive piston allowing it and its rack to return to its initial position by the reaction of its spring.

It is during this tape advance cycle described above that the pilot valves of the hydraulic system must be physically locked by pressure in line 88 from responding to the tape holes as they move under the air reader head 111, and at the same time, the sense hoses 12, diaphragms 102 and air reader ports must be flushed out with a reverse air blast to purge the air sense system of any contamination from the previous read cycle. Line 76 to the purge control 99 and isolating valves 98, respectively, causes both valves to move to the left, valve 98 moving against the reaction of its spring 108. The transfer of the multiple land isolating valve 98 will expose all of the purge hoses 101 to the port of the transferred purge control valve 99 and, at the same time, shut off the air pressure to the air manifold l 10 by the scissoring action of the extreme left-hand land of the isolating valve 98.

The port 100 of the purge control valve exposed to its 10 psig port 109 provides a reverse air flow through the 16 diaphragm chambers, sense hoses and the air reader head ports with the foreign matter, if any, being expelled between the air reader head and tape to the atmosphere. Following this purge cycle, the entire reading circuit and diaphragms must be depressurized before releasing the locked diaphragm actuated pilot valves. In order to accomplish the depressurization, the purge control valve must be returned to its initial posi- 

1. In a damping mechanism having a relatively fixed member, a movable member and damping means coupled to said movable member for exerting a damping force thereon, the improvement comprising a selectively actuated locating means including a piston in a piston chamber for positively urging said movable member towards a preselected position relative to said fixed member during actuation of said piston, said piston being mechanically coupled with said movable member by rigid means during urging by said piston of said movable member towards said preselected position, and control means adapted to operate said locating means subsequent to damping by said damping means, whereby said damping mechanism is adapted to have its movable member secured to a load to provide damping while initially passing beyond said preselected position freely and then said control means subsequently providing accurate positioning by actuating said piston for driving said load to said preselected position.
 2. Apparatus in accordance with claim 1 wherein said selectively releasable means comprises a piston for driving said movable member towards a preselected position, during engagement thereof.
 3. In a mechanism having a relatively fixed member, a movable member and damping means coupled to said movable member for exerting a damping force thereon, the improvement comprising selectively releasable means for positively positioning said movable member relative to said fixed member, during engagement of said releasable means, said selectively releasable means including a pair of back-to-back pistons movably contained within a piston chamber each having a projection directed outwardly from said chamber, each of said pistons being adapted for engagement with a corresponding confronting surface of a part secured to said movable member, and an actuation inlet for fluid to said piston chamber adapted for connection to an actuator, whereby said movable member is driven by said pistons to a home position in a direction corresponding to the piston in engagement during actuation of said pistons by application of fluid pressure to said actuation inlet.
 4. A housing including a pair of substantially parallel cylindrical bores comprising piston chambers, a first bore filled with fluid including a damper piston reciprocable within said first bore, said piston having shafts extending from opposite ends thereof, a pair of bars each one being secured to one of said shafts extending from said damper piston for reciprocation therewith, a second bore of said pair of bores, said second bore carrying a pair of locating pistons free to move in said second bore reciprocably each of said locating pistons having a plunger extending outwardly towards one of said bars secured to one of said shafts, and guide means for retaining said damper piston and said bars in alignment, inlets to said first bore at opposite ends thereof connected in a bypass circuit filled with fluid including an orifice for providing a limited velocity of flow of fluid through said bypass circuit for permitting damped motion of said damper piston in said first bore, an inlet to said second bore for selective application of fluid pressure to said locating pistons.
 5. Apparatus in accordance with claim 1 wherein said damping means is displaceable between extreme positions, and said locating means urges said damping means to a central position intermediate its extreme positions of displacement during actuation of said locating means.
 6. Apparatus for damping a load and subsequently locating the load accurately comprising damping means secured to a load, locating means for driving said damping means intO a predetermined location, control means connected to said damping means for operating said locating means subsequent to damping of motion of said load to drive said damping means into said predetermined location. 